Gene duplications are a ubiquitous feature of eukaryotic genomes. However, we know relatively little about the evolutionary forces responsible for their preservation in, or loss from, the genome. The proposed research involves a resequencing survey of duplicated loci in three Drosophila species, D. melanogaster, D. simulans, and D. yakuba. We will also obtain mate pair sequencing data using the Illumina Genome Analyzer platform to survey D. simulans and D. yakuba species for segregating duplications. The resequencing data set will be used to quantify the extent of selective constraint within, and adaptive divergence between duplicated loci. Additionally, these data will provide valuable insight on the extent of ectopic gene conversion in the genus. The mate pair data will be used to infer the frequency spectrum of coding and non-coding duplications in all three species, and to quantify the extent to which such segregating variation may be deleterious or adaptive. We will also use these data to look for regions of the genome where polymorphism and divergence for duplication may be uncoupled, indicating a role for natural selection on the evolution of gene families. PUBLIC HEALTH RELEVANCE: The gain and loss of genes over time is a major contributor to the evolution of genome structure, and variation in the number of genes is a contributor to phenotypic variation and disease within human populations. This study will use the fruit fly Drosophila melanogaster as a model system to elucidate the various evolutionary forces acting on recently duplicated genes, including those that are fixed within species as well as those segregating as polymorphisms. The design of the proposed research is intended to complement the Drosophila Population Genomics Project (DPGP, http://www.dpgp.org), which is focusing its near-term effort on D. melanogaster, by providing comparative data on duplicate loci and structural polymorphism in two other species from the genus, D. simulans and D. yakuba. 1